Astrometric Data
The astrometric parameters which serve as input to the stellar motion model including position at a specified epoch, proper motion and parallax.
Available for these objects: Star
Type: Fixed data.
Availability: Reports
Data Provider Elements
| Name | Dimension | Type | Description |
|---|---|---|---|
| Epoch | DateFormat | Real Number | The reference epoch for the object. |
| Julian Epoch | Unitless | Real Number | The epoch of the astrometric data given in Julian epoch format. The Julian epoch is related to the Julian date by the expression JD = 2451545.0 + (yyyy.yy - 2000.0) x 365.25, where 2451545.0 (TT) represents the standard J2000 epoch. |
| Reference Frame | Unitless | Text | The reference frame of the astrometric data: J2000 or ICRF. |
| Right Ascension | LongitudeUnit | Real Number | The signed angle measured from the X axis to the projection of the position vector into the XY plane. The angle increases in the direction found by the right hand rule about the Z axis. |
| Declination | AngleUnit | Real Number | The signed angle measured from the XY plane to the position vector, where positive angles are used for locations above the XY plane, and negative for those below. |
| Proper Motion RA | AngleRateUnit | Real Number | The component of proper motion that is defined by the angular rate of right ascension multiplied by the cosine of declination. |
| Proper Motion Dec | AngleRateUnit | Real Number | The component of proper motion that is defined by the angular rate of declination. |
| Radial Velocity | Rate | Real Number | The radial velocity of the star. |
| Parallax | AngleUnit | Real Number | Annual parallax. |
| x | Unitless | Real Number | First component of the selected vector expressed in the reference set of axes. Defines projection of the vector onto the x-axis of the reference set. |
| y | Unitless | Real Number | Second component of the selected vector expressed in the reference set of axes. Defines projection of the vector onto the y-axis of the reference set. |
| z | Unitless | Real Number | Third component of the selected vector expressed in the reference set of axes. Defines projection of the vector onto the z-axis of the reference set. |
| vx | Unitless Per Time | Real Number | X component of unit vector from the solar system barycenter to the star at the associated epoch. |
| vy | Unitless Per Time | Real Number | Rate of change of Y component of unit vector from the solar system barycenter to the star at the associated epoch. |
| vz | Unitless Per Time | Real Number | Rate of change of Z component of unit vector from the solar system barycenter to the star at the associated epoch. |